ASTM D8331/D8331M-20

4.1 Coating film thickness plays a critical role in the performance of the final product. This includes physical properties (abrasion/scratch resistance, color, gloss), chemical properties (solvent resistance), corrosion resistance, and long-term durability (color change, chalk, fade).

4.2 The non-destructive measurement system based on ruggedized optical interference transforms signal outputs in coating film thickness using digital formulas (or “recipes”) which are reproducible from one instrument to another.

4.3 The ROI measurement unit takes a significant number of measurements which can be read in a determined period of time and each of these data points is recorded and reportable.

4.4 Due to the number of variables that can affect film thickness during application and the number of variables that must be set in the measurement unit while determining a recipe, it is important for the producer and the user to agree upon recipe settings depending on the coating system.

1.1 This test method encompasses measuring the film thickness of a coil coated organic coating layer. Operators can use this method in process during the coating application or in a laboratory setting.

1.2 This test method does not specify the expected film thickness/test results for a coating, nor the specific “recipe” file needed to measure a coating.

1.3 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system are not necessarily exact equivalents; therefore, to ensure conformance with the standard, each system shall be used independently of the other, and values from the two systems shall not be combined.

1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.

1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.